As chips have decrease in size and cost, they have been dispersed into the communications networks.
In the early days of computing, say the 1950’s, computers had to be operated directly through devices such as Hollerith punch cards and only one person at a time could use the machine. With the development of time-sharing computer operating systems many people could use the machine simultaneously ( or so it would seem for all practical purposes).
If time-sharing users were distant from the central computer, a device called a modem converted the digital signals into electrical signals compatible with the voice telephone system. The process is reversed at the computer end.
New interconnection methods eliminate the modem intermediaries. ISDN interfaces, local area networking and digital subscriber lines (DSL) of various kinds keep the signals digital along the entire path.
